AC, DCEN and DCEP. When to use them. When not to use them. Part3
DCEP, or Reverse Polarity is the standard polarity for MIG and for Stick welding. In MIG, if it uses gas only, without a flux or metal core, it will require electrode positive. Dual shield and metal core can vary.
Any MIG hard wire welding accidentally with DCEN, will result in globby welds, with an unstable arc and frequent arc outages. As for the required polarity welding with Stick, almost all welding is done with Reverse polarity. This is because the electrons flowing from the negative work to the positive electrode help to deposit the metal at a regular pace and, though it is counter-intuitive, it actually helps to increase penetration.
DCEP provides a more stable arc in general in stick welding, but for welds requiring light penetration, use DCEN if the electrode is designated to run either polarity.
Although years ago, TIG welding was briefly done with DCEP during the war years on aluminum aircraft, it required large electrodes and low currents or the tungsten would overheat and is no longer considered acceptable since the development of AC welding in TIG for aluminum. DCEP provides plenty of cleaning for aluminum, but is not used because of the limitations of the tungsten’s heat range.